The broad objectives of this project are to evaluate the influence of genetic controls on the tumor-host immunological relationship - both at the level of the nature of the cell surface antigens that can provoke such tumor responses, and at the level of host genetic control operating in the various mechanisms of "immune" recognition. These studies include: (1) an analysis of the expression of various H-2 and I region antigens on a variety of tumor cell types; (2) an analysis of the expression of Hh antigens on normal and tumor cells, and of the nature of the genetic control of host responses to Hh antigens; (3) analysis of the natural killer cell reactive with certain tumor cells, and its possible role in immunosurveillance; (4) determination of the possible role of MHC gene products in tumor specific antigens on lymphoid and plasma cell tumors; and (5) analysis of possible Ir genetic control of T cell mediated immunity against various tumor associated antigens.